The guitar, in one form or another, is one of the most popular musical instruments in use today and is used in a plethora of musical genres. The “voice” any particular guitar has is based on its design and construction. The present invention relates to a steel string acoustic (hollow body) guitar that gets its strength and tonal quality from the incorporation of various unique structural design elements in the guitar's body, particularly, from the from the use of a laminated, domed top and tunable braces the stringed musical instrument's soundboard.
Luthiers strive to produce the best sounding guitars that they can. To accomplish this they must build guitars that emanate tones (notes) pleasant to the ear, and that produce maximum sound amplification. Sound is any change in air pressure that our ears can perceive. Pleasant sound, is generally known as the tones or notes of the major and minor scales. These notes are denoted by the frequency of oscillation that causes the change in air pressure that our ears perceive as that note.
A tonal quality is distinguished as clear (or “true”) when the ear perceives a solo frequency of oscillation or a combination of a very small number of related frequencies of oscillation (harmonics) rather than a combination of hundreds of random frequencies of oscillation. Although the generation of good tonal quality is a function of several elements such as the materials of construction, the volume, the shape and taper of the body as well as the configuration of the upper and lower bouts, primarily good tonal quality is accomplished by a soundboard that produces a minimal number of random frequencies of oscillation. To do this the soundboard must undergo very little localized distortion so that it can vibrate uniformly across it's entire surface. Accomplishing this requires the soundboard to be uniformly rigid. Since the soundboard (guitar top) is only secured to the sides about it's periphery, the central region about the sound hole is free to distort and flex more than the periphery. Additionally, the six strings on an acoustic guitar impart between 90 to 200 pounds of angled tension upon the bridge which place further distortion forces on the soundboard's central region. The prior art traditionally has installed stiffening or strengthening braces on the underside of the top to account for this.
This new guitar structural design utilizes a stronger, more uniform soundboard through the incorporation of a laminated honeycomb torsion box construction in conjunction with a domed top. This rigid design eliminates the need for such braces in the lower bout and upper bout of the guitar top.
In a different foam laminated design, the back of the guitar and the sides have been made thicker and stronger but lighter thereby eliminating the need for back and side structural braces.
It is known that the tonal quality of a soundboard also changes with age. Since this cannot be adjusted once the guitar has been constructed, another way to improve tonal quality is by “tweeking” or fine adjusting of the soundboard (or bottom) by the use of adjustable braces strategically placed on the underside of the soundboard or back of the guitar. These can be used to compensate for other elements that affect tonal quality such as design inadequacies, temperature and humidity. Since the body of a guitar favors some frequencies (amplifies them better) and discriminates against others (does not amplify them as well), tweeking the guitar by using the adjustable braces allows the tuner to optimize the tonal quality of the guitar for the changing circumstances.
It is known that the tonal quality of a stringed instrument changes with time. Continuous vibrations as those experienced with regular use of a musical instrument changes the nature and resonance of the wood. (The molecular bonds of wood actually break because of vibration and that this what affects the tonal qualities.) This results in a change in the stiffness of the soundboard and a decrease in the dampening coefficient, (a measure of cycles of vibrations emanating from the material). Lower damping coefficients mean that a single note is heard longer, which is considered a beneficial attribute. Both factors are known to help provide more pleasant tones in spruce, mature pine and other woods used in instrument sounding boards. With tuneable braces this improved sound can be accomplished earlier.
Henceforth, a guitar body with a minimal number of braces especially in the lower bout region, would fulfill the long felt need in the stringed instrument industry. This new invention utilizes and combines both known and new technologies in a unique and novel configuration to overcome the aforementioned problems of the prior art.